Question 1: Define a convex lens and explain how it affects parallel rays of light.

Answer: A convex lens is a converging lens that bulges outward and causes parallel rays of light to converge to a focal point on the opposite side.

Question 2: Describe the primary difference between a concave lens and a convex lens in terms of light refraction.

Answer: A concave lens is a diverging lens that causes light rays to spread apart, whereas a convex lens converges light rays.

Question 1: An object is placed 30 cm in front of a convex lens with a focal length of 15 cm. Calculate the image distance (v) using the lens formula: 1/f = 1/u + 1/v.

Answer: v = 10 cm (positive, real image)

Question 2: A concave lens with a focal length of 20 cm forms an image 60 cm from the lens. Determine the object distance (u) using the lens formula.

Answer: u ≈ -15 cm (virtual object position)

Question 1: Identify three variables that would affect the image size when using a convex lens in an experiment.

Answer: Object distance, focal length of the lens, and distance between the lens and screen.

Question 2: State two safety precautions to consider when setting up a lens experiment involving bright light sources.

Answer: Avoid direct eye exposure to bright light and ensure the setup is secure to prevent accidental falls or breakage.

Question 1: A convex lens with a focal length of 10 cm produces a real, inverted image when an object is placed at 15 cm from the lens. The image is formed 30 cm on the opposite side. Calculate the object distance and verify consistency with the lens formula.

Answer: Object distance u ≈ 6.67 cm; calculations using 1/f = 1/u + 1/v confirm the data.

Question 1: Explain how convex lenses are used in magnifying glasses and the importance of focal length in this application.

Answer: Convex lenses in magnifying glasses produce a virtual, enlarged image of objects when placed within the focal length; shorter focal lengths produce larger magnifications.

Question 2: Describe a real-world scenario where concave lenses are utilised and explain the physics behind their function.

Answer: Concave lenses are used in eyeglasses for nearsightedness; they diverge light rays before reaching the eye, helping focus the image correctly on the retina.